Process of and apparatus for making natural-gas substitute.



C. S. PALMER.

PROCESS OF AND APPARATUS FOR MAKING NATURAL GAS'SUBSTITUTE.

APPLICATION FILED OCT. 5. 19H- 1,268,763. I Patented June 4:, 1918.

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Specification of Letters Patent.

Patented Junie fidld.

Application filed flctobcr 5, 1917. serial Ito. 1%,8M.

To all whom it may concern:

Be it known that 1, CHARLES S. PALMER, a citizen of the United States, residin in Pittsburgh, county of Allegheny,and tate of Pennsylvania, have invented certain new and useful Improvements in Processes of and Apparatus for Making Natural-Gas Substitute, of which the following is a specilication.

My invention relates to improvements in the manufacture of combustible gases from coal and has for its objects the economical and convenient production of a coal-andwater-gas mixture from bituminous coal, the manufacture preferably being carried out by successive operations in the same apparatus, although obviously if desired the successive steps of the manufacture may be conducted in different units of the plant.

My invention has for its objects the production of a fuel gas which has a relatively high thermal value and yet is so low in cost as to compare favorably from a thermal standpoint with natural gas having 1,000

B. T. U. per cubic foot and costing ten cents per thousand cubic feet, or with bituminous coal having 10,000 B. T. per 1b., and costing $2.00 per ton.

At the present time the principal methods employed in the manufacture of fuel gases comprises the coal or illuminating gas method which produces gas consisting essentially of methane and hydrogen with a minor percentage of CO and heavier hydrocarbons and having a thermal value of about 500 to (300B. T. U. per cubic foot and yield ing about 65% of coke with numerous byproducts as'tar, ammonia, benzene, etc.; the Water gas process which yields an uncarbureted product that consists essentially of hydrogen and carbon monoxid and has a thermal value of 350 B. T. U. per cubic foot; and the producer gas process which yields a gas which has a very low thermal value of but 150 B. T. U. per cubic foot and consists principally of nitrogen and carbon monoxid with a minor percentage of hydrogen. The coal gas process as at present practised, especially when produced in coke lgproduct'ovens, isin a very high state of e ciency. In the intermediatev water gas process, however, which 1s usually the basis of the common city gas supply, the present process is highly wasteful, in fact about 50 to more coal is consumed inthe process merely for maintaining the necessary heat for. the water gas reaction than is necessary, 11. e., the present practice consumes about 50% of hard coal or coke for maintaining the reaction temperature, whereas, theoreti eally but about 30% should be required. Primarily this is due to the wasteful em ployment of an intermittent air blast for periodically restoring the temperature of reaction as well as being due to the great len h. of time required when employing the mo ern retorts in order to heat the contents to the reacting temperature and the consequent serious loss of heat throughout said period by radiation and otherwise.

My invention is fully set forth and described in the accompanying drawings and specification forming a part thereof, in

wh1chgigure 1 is a longitudinal vertical section; an

Fig. 211s a transverse vertical section along the line 2-2 of Fig. 1. i

In the drawings the reference numeral 1 designates the fire-brick walls of the heating chamber having the usual heating fines therein and 2 designates a long narrow chamber or retort, preferably for example of about 20x10 and 8" to 10" wide having a V-shaped bottom, the walls being about 1} in thickness. The heating chamber communicates with the usual checker-work of regenerator furnaces positioned below the same (not shown). Preferably such retort is constructed in sections and the same are constructed of a highly refractory,'non-oxidizable metal such as xii-chrome steel, though nickel steel or nickel-may be also employed in lieu thereof. Suitable poke holes a and charging holes I; are provided at the top communicatin with a suitable discharge reservoir for t ecoke residuum at the end 3 and having a suitable cast iron door t covtions (2 at intervals along the top in order of the retort, as shown. llhe lower section preferably has. cast iron extensions 3, 3-

y, weaves to uniformly admit steam into the bottom of the retort.

Referring to th drawin and the construction shown therein, t e operation of the process is as follows:

Sufiicient bituminous coal is introduced through the charging holes to substantially fill'the entire retort. Such coal is then coked at the usual temperature by means of heat conducted thereto from the gases in ues through the highly conductive, thin, metallic walls of the retort. The gas so generated is conducted ofi' through the p1 e 5, to containers or reservoirs therefor an the coke residuum may be removed into another similar retort through the outlet 3, in order to subject the same to the second stage of the ably about very 'hot-reduc process, but preferably said second stage is.

conducted in the'same retort. The coal gas so obtained may be suitably scrubbed and otherwise treated in the usual manner to obtain the lay-products therefrom, such as tar, almmonia, benmol, etc.

Owing to the high conductivity of the thin walls of my retort, which are preferthick, and should not exceed 1}" in thickness in any event, even the cutting may be accompllshed in a shorter s ace of time than the present process and as a consequence there is but a minimum of tool and time required for this stage of the process.

In order to produce water gas from the coke residuum of the first stage of the recess, the retort is firstsufiiciently heated y the negenerator furnace-gases, passing through the flues so as to maintain the mass incandescent by indirect heat, only, throughout the second stage of the process, prefer ably at about 110W 0. Steam is then introduced through the steam-line 6 in su licient quantities to convert the incandescent coke into Water gas according to the formula Preferably the steam is superheated, superheatingbeing decidedly more eficier t. Qwing to'the high heat-conductivity as above stated, of the thin metal walls of my retort,

this second stage of the process is completed very rapidly as compared with the usual procedure and the periodically injected hot lasts oi atmospheric "airare not required in soon become superficially loaded with carhon, When subylelicted to direct contact with g gases havin a high carbon content, particularly at tem ratures between M00 and NW0 6/ No oniy is such carbon physically deposited upon and 0 s %@g and substantially obtained.

able.

throughout the exposed surface layer of the structurally, often becoming weakened to such an extent as to in many cases even crumble to pieces While being subjected to temperatures up to 1100 (3., and furthermore its specific heat conductivity becomes very greatly reduced. Under the conditions however to which the nickelous envelop is subjected during the operation of my process, the inner portion -thereof is protected from the carbonizing or oarbid forming action of the reducing gases in the retort, because of the fact, as my investigations have shown, that the nickelous portion of the envelop is extremely thin and, at the high temperature to which it is subjected, is at least partially pervious to the passage thereinto of the strongly oxidizing external aseous heating medium, such as the produceras and hot air -mixture which is preferably employed by me. The result is that the deleterious action of the carbonizing and carbid-forming gas within the retort upon the inner exposed layer of the envelop is substantially, if not entirely, revented, and instead of the structure of t s envelo beingseriously weakened and the specific heat conductivity of the envelop being greatly diminished, as would ordinarily be'expeeted by those familiar with the' beha'vior of nickel and its alloys consisting essentially of nickel, the envelop is found to be extraordinarily durable and even after repeated operations of myprocess herein to retain to a remarkable degree its specificheat conductivity.

In view of the high conductivity of the walls of the retort and the elimination of the necessity of injecti a blast of heated air thoreinto as aforesai dl am able to obtain from the cake a maximum yield of a water as mixture having a minimum amount oftre t a nitrogen, 'i. a, about .5% and less than 1% in all cases where the process is properly carried out.

The coal obtained has a calorific value of about flm'and water gas mixture of about 4&0 -B. l. U. per cubic foot. By a suitable mixing-ct the two foregoing a calorific value of 4100'tq-5QWB. 'l. W. per cubic toot can be Who aresaid i i-chrome alloy approximo in capacity l r M; I i-ohnorno affley. approirirnates 12%? C. moltia point -d is'rolat vely non-oxidizit cesponels substantially ence ing of the reactin mass due to the fact that the non-oxidizab e, highly-resistant, thin,

metal wall promotes a quick and ready transfer or the large amount of heat required from the outside to the inside of the retort in which the water gas reaction is proceeding, whereas, were the walls constructed relatively thick, say in excess of 1%, even though they were of metal. such transfer of the necessary heat to accomplish the quick conversion of the coke or hard coal into water gas could not be accomplished, and prolonged heating ofthe coke b r the periodic injection thereinto of hot b asts of air would be necessary in order to revent the temperature falling below the point at which the water gas reaction proceeds eficiently, because the reaction which occurs at lower temperatures, must be avoided in order to obtain an eflicient and satisfactory substitute for natural .13.5. Furthermore, the residual coke from te'second stage of my process containing however .much residual good material, may be discharged, through partly housed and closed ways and crus ing rolls, (not shown), to a producer gas plant which consumes the resid ual coke, producing much producer gas of low thermal value but which is'adapted in suitable combination with heated air, econominers and regenerators to heat the coal and water gas retorts; in the first two stages of the process.

In my preferred process I also employ nichrome steel or other correspondingly highly resistant non-oxidizable metal in the steam hue and the superheaten-smce not only am I thus able to superheat the steam to the retemperature considerably in excess of ordinary superheated steam, for example, from 750 C. to 1100" 0., is believed to materially promote thedissociation of the steam, there by increasi the chemical activity of its elements with t e consequence that the formation of hydrocarbons by the interaction of hydro of the steam and the carbon of the co is accordingly facilitated. Such a superheater is illustrated in Fig. 1 in which a coil 7 is positioned .in a superheating chamber 8, the said chamber being provided notion in temperature I permits of the reactlon being completed in a with gas inlet'and outlets 9 and 10 respectively. In this construction the coil 7 and the entire Steam pi 6 are constructed 0nichrome steel, mc el-steel, nickel or other suitable, hi hly refractory, substantially non-oxidizab e, metal.

While nickel itself, when employed for the retort or the superheater piping forms a thin superficial coating of nickel oxid, I have found that the formation of this crust does not seriously retard the conduction of script-ion, the employment of a highly resistant, non-oxidizable, metal retort, having walls not exceeding 1?; inches in thickness, has the following important advantages over the present coal gas, water es and producer gas processes as commercially practised:

First, it avoids the necessity for quenching the eokeproduced in the usual coal-gas process, after the removal of the coke from the coke oven and prior to its introduction in the water-gas or producer-gas retort, and thereby substantially all of the heat retained in the coke at the end of the coal-gas stage is conserved, since-in my process, as above stated, the water-gas process is preferably conducted in the same retort as the coal-gas process immediately followin the comple-' tion ,of the latter.

' Second, it'avoids the necessity for the use of an intermittent air blast to maintain the reacting temperature and thereby prevents the dilution of the gas with large amounts of nitrogen from the heated air blast, and also the maintenance of the uniform temperature enables me to obtain a much more economical and increased yield of gas of a more uniform composition.

Third, the employment of non-oxidizable highly resistant metallic walls, which should not exceed 1% inches in thickness, and are preferably J inchin thickness, as a substitute for cast iron or other oxidizable metal retorts or clay and silica retorts now used,

much shorter eriod of time because of the coal gas reactlon belng continuous in but a fraction of the time required when the present retorts, employed.

Fourth. One of the advantages of employwhic heat extremely slowly, are

ing high-pressure sipezrheated steam at a temperature of 750 0 1100 C. is believed to be due to the formation of increased amounts of higher hydrocarbon due to the increased dissociation of the steam since it is well known that the addition of one or more atoms of carbon. or hydrogen to a hydrocarbon in manycases very substantially increases the thermal, value thereof.

iron in. the iron offuel'in a space havin'g'hn consists principally with iron in the This is shown by the following table in which is ven the relative thermal units per cubic eat of difi'erent hydrowrbonszper cub. ft. on, 11, 917 1,554 Call, 3, 954 00 9 i o H, 12,420 1, e 02H, 11,931 1, 677 n, 34,180 ,an on, 13, 320 1, 010

In some cases, depending upon the character of the coal and the byroducts de sired, a small amount ofsuper eated steam can be advantageously injected into the charge in the first or coal-gas stage of the process.

By employing my improved process I can continuously, as distinguished from intermittently, produce 500 to 1000 cubic feet of water-gas per square foot of heating surface in every 24 hours, the same approximating the following average composition:

Obviously, in those cases where the extension 3 is not in communication with the discharge reservoir for the coke residuum resulting from the second or water gas stage 'of the process, said extension or end 3 is closed in the same manner as extension 3 by a cast iron 'door (not shown).

The employment of platinum, gold, iron, (and by iron I include iron having such carbon content as to come within the range commonly termed steel,) as the material of the envelop referred to in the process claims herein, or, as the material of the retort referred to in the apparatus claims herein, is specifically disclaimed.

The expression a metal associated with group in Mendeljeifs table and of greater atomic weight, than iron, refers to metals which are associated with iron in the group commonly known as the iron group consisting of iron, atomic weight 55.84, nickel, atomic weight 58.65 and cobalt, atomic weight 58.97.

aving thus described my invention, what 'I claim and desire to secure by Letters Pat- -1. In'the manufacture of water-gas, the process, which consists confining a charge envelop which of a metal' a'ssociate'd iron'group in Mondalejefis table and of r ter'atomic'weight than the action of iron, said envelop not exceeding 1'} inches in thickness, being of good heat conductivity and not deleteriously affected when subjected to the action of a mixture of producer gas and air heated to a temperature of 1100 (1., for prolonged periods of time, supplying suflicient heat to said charge through said conductive envelop from a strongly oxidizing, highly-heated, gaseous medium caused to contact with the outer surface of said envelop, to promote the wateras reactionv in said charge, maintaining sald temperature by conduction of heat to said charge through said conductive envelop without the direct introduction to said chamber of substantial quantities of an air blast, simultaneously supplying a snfiicient quantity of steam to said charge to eflect the water-gas reaction so as to produce a strongly, reducing, highly-heated, gaseous medium in contact witha substantial portion of the inner surface of said envelop.

2. In the manufacture of water-gas, the process which con .ists in confining a charge of fuel in a space having an envelop which consists principally of a metal associated with iron in the iron group in Mendeljefi"s table and of greater atomic weight than iron, said envelop not exceeding 11} inches in thickness, being of good heat conductivity and not deleteriously adected when subjected to the action of a mixture of producer gas and air heated to a temperature of 1100 (3., for prolonged periods of time, supplying sufiiclent heat to said charge through said conductive envelop from a strongly oxidizing, highly-heated, gaseous medium caused to contact with the outer surface of said envelop, to promote the water-gas reaction in said charge, main taining said temperature by conduction of heat: to said charge through said conductive envelop without the direct introduction to said chamber of substantial quantities of an air blast, simultaneously supplying a suficient quantity of .highly superheated steam, ata temperature in excess of 7 50 C., to said charge to eliect the water-gas reaction, so as to produce a strongly, reducing, highly-heated, gaseous medium in contact with a substantial portion of the inner surface of said envelop and then recovering the evolved gas. a

3. The process of manufacturing fuel as, which consists in confining a charge of b1tuminous coke against the, lngress of air in a space having an envelop which consists principally of a metal associated with iron 1n the iron group in Mendeljefis table and of greater atomic weight than iron, said envelop not exceeding 11} inches in thickness, being of good heat conductivity and not deleteriously afl'ected when subjected to a mixture of producer gas and air heated to a temperature of 110i) U,

tile 'matter is expelled, withdrawing the from said charge and maintaining said tem-' perature until substantially all of the volaliberated gas from said chamber, then conductin suflicient heat through the envelop of. sai space from a strongly oxidizing, highly-heated, gaseous medium caused to contact with the outer surface of said envelop to elevate the temperature of the residual coke therein so as to promote the water-gas reaction, maintaining the said reacting temperature of said coke, while simultaneously introducing steam, without the substantial introduction of oxygen, for a suflicient time to convert the greater part of said coke into water-gas, and thereby produce a strongly reducing, highly-heated, gaseous medium in contact with a substantial portion of.the inner surface of said envelop and recovering the evolved water g 4. In the manufacture of water-gas, the process which consists in confinin a charge of carbonaceous fuel in a space aving an envelop which includes a medium consisting principally of nickel, said envelop being of good heat conductivity and being sufiiciently thin to be substantially penetrated into by an external strongly oxidizing, highly- 7v heated, gaseous medium brought into contact with the outer surface of said envelop and also sufiiciently thin to permit of the substantial neutralizing by said oxidizing medium of thegrapliite and carbid-forming tendency of a strongly reducing, highlyheated gaseous medium simultaneously brought into contact with the inner surface of said envelop, said envelop being substantially non-oxidizable when subjected to the action of a mixture of producer gas and air heated to a temperature of 1100 C., supplying suiiicient heat to said charge through said conductive envelop, from a strongly, oxidizing highly-heated, gaseous medium caused to contact with the outer surface of said envelop, to promote the water-gas reaction in said charge, maintaining said temperature by continued conduction of heat from said gaseous medium through said conductive envelop to said charge without the direct introduction into said chamber of substantial quantities of 'air, simultaneously supplying a suficient quantity of steam to said charge'to efiect the water-gas reaction, so as to reduce a strongly reducing, highly-heate gaseous medium in contact with a substantial portion of the inner surface of said envelop stantially closed retort positioned in said chamber, a substantial portion of said retort being relatively narrow and having extremely thin, refractory, substantially noncorrosive walls consisting principally of nickel and not exceeding one and one-half inches in thickness, an outlet conduit communicating with the interior oi. said retort for conducting gas therefrom and means for distributing steam throughout the interior of said retort.

6. In an apparatus for producing watergas, the combination comprising a heating chamber provided with a gas-inlet, a substantially closed retort positioned in said chamber, a substantial portion of said .retort being relatively narrow and having thin, refractory, substantially non-corrosive walls consisting principally of nichrome and not exceeding one and one half inches in thickness, an outlet conduit counicating with the interior of said retort for conducting gas therefrom and means for distributing steam throughout the interior of said retort.

7. In an apparatus for producing watergas, the combination comprising a heating chamber provided with a gaainlet, a substantially closed retort positioned in said chamber, a substantial portion of said retort being relatively narrow and having thin, refractory substantially non-corrosive walls not exceeding one and one-half inches in thickness composed of a metal associated with iron in the iron group in Mendeljefis table and of greater atomic. weight than iron an outlet conduit communicating with the interior of said retort for conducting gas therefrom and means for distributing steam throughout the interior of said retort.

In witness whereof, l have hereunto set my hand at the city of Pittsburgh, county of Allegheny and State of Pennsylvania, this third day of October, 1917.

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